We know you sometimes have burning questions that can best be answered by a pharmacist. Our feature, Ask Your Pharmacist , seeks to address some of those issues. Send your questions to healthandwealth@jamaicaobserver.com.

Question: Why can’t I have dairy with some antibiotics?

Answer: Fortunately, not all antibiotics interact with dairy products, but there are some that will be dispensed with the warning to avoid dairy. Some common antibiotics that will trigger this warning are Tetracycline, Doxycycline, Ciprofloxacin, and Levofloxacin.

Tetracycline and doxycycline

Tetracycline and doxycycline are antibiotics that work by disrupting protein formation in bacteria. Proteins are the basic building blocks for the cells of the bacteria. If there is no protein (or damaged protein), the bacteria cannot grow or flourish and will eventually die.

If you have been to the dentist for an abscess or an extraction, you have probably received doxycycline.

Ciprofloxacin and levofloxacin

Ciprofloxacin and levofloxacin work by destroying the DNA (deoxyribonucleic acid) of the bacteria. The DNA is the brain of the cell, so if the DNA is destroyed, the cell cannot function. The bacteria will eventually die.

If you have ever gone to the doctor for a urinary tract infection (UTI), you might have received ciprofloxacin.

Dairy warning

These antibiotics are always dispensed with a warning to avoid dairy products. Dairy products include milk, butter, yoghurt, ice cream, and cheese. The danger really stems from the calcium in these products.

Calcium in supplements, antacids, and fortified fruit juices are just as dangerous as the calcium in dairy products. Hence, many times, the pharmacist will go on to say that antacids and multivitamins/mineral supplements should be avoided for the duration of treatment with the antibiotic. In actuality, calcium-containing products can be had two hours before or after taking the antibiotic. This will ensure that the stomach is clear of the calcium by the time the antibiotic gets there. However, it can be difficult to get the timing right, so it might be best to just avoid these products for the duration of the treatment.

Calcium is needed for the development of strong teeth and bones. It is an essential mineral to have in the diet, so it might seem strange to advise patients not to partake of any calcium. The good thing is that most times antibiotic treatment therapies are short — about a week long — so you won’t have to stay away from dairy and calcium-containing supplements for an extended period.

Chelation

How does dairy/calcium affect these antibiotics though? The calcium in dairy products interacts with the antibiotics in a process called chelation. Chelation is just a fancy way to say that the calcium binds to the antibiotic molecules and changes the chemical structure of the antibiotic. This makes it quite difficult for the body to absorb and utilise the antibiotic.

Of course, if the body cannot absorb the antibiotic into the bloodstream, it will not get to the site of infection to kill the bacteria. Instead, the antibiotic might just stay in the digestive tract and be passed out of the body without carrying out its job. This may result in treatment failure. Even if the calcium affects just half of the drug, you’re only getting half the dose, which could mean the infection isn’t destroyed by the end of the course. In either case, the treatment would be ineffective.

Chelation can occur when any form of calcium is present in the stomach at the same time as the antibiotic, so pay attention to your diet, any supplements that you might be taking, and antacids that you might use to relieve heartburn.

Some patients think the important thing is to simply take the medication once or twice per day, as is written on the label. However, the auxiliary instructions are very important to ensure success of the therapy. After all, some antibiotics can be pretty expensive. You want to ensure that you get value for your money by utilising the drug properly. You also want to engage the shortest route to regain good health.

If the antibiotic therapy is ineffective because of chelation caused by calcium in your food or supplements, you will have the infection for longer and you might actually be prescribed another round of antibiotics to help fix the initial botched attempt. This is certainly not a desirable outcome.

The next time you get antibiotics, be sure to ask if it is okay to have dairy with it. If the pharmacist advises you against dairy, pay a little more attention to your diet. You can successfully substitute lots of things for dairy products. Look at your food labels, too, to ensure that calcium is not hiding in your favourite orange juice or cream-filled biscuit.

Novia Jerry Stewart, MSc, RPh, is a pharmacist who specialises in ophthalmic care. She may be contacted at novia_jerry@yahoo.com.